Employee Relations Minister Damien Tudehope says the government has withdrawn its requirement that a new enterprise agreement be reached before it begins modifications the union wants on the New Intercity Fleet (NIF).
The sticking point in the protracted negotiations has been the government's insistence the agreement be locked in before the modifications begin.
"After appropriate testing and warranty confirmation, the government will immediately authorise the commencement of work to make the alterations to the NIF," Mr Tudehope said in a statement on Monday.
"The offer is conditional upon the rail unions agreeing that, pending the finalisation of the new enterprise agreement, all unions will call off any further industrial action."
The mothballed NIF has been at the centre of negotiations with the Rail, Tram and Bus Union, which maintains the trains are not yet safe to operate in NSW.
Transport Minister David Elliott has put the price of modifications to the fleet at $1.1 billion, or $264 million "depending on how you account for the cost".
The union has been conducting extensive industrial action including targeted, rolling stoppages throughout August.
The action is due to culminate with workers refusing to operate foreign made trains on Wednesday, which would affect about 70 per cent of the fleet..
The offer will be discussed at a meeting between rail unions and government officials on Monday.
"The NSW government urges the rail unions to accept this offer, and put a stop to its industrial action, today," the government statement said.
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